Funding:This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661The Facility for Rare Isotope Beams, a new national user facility funded by the U.S. Department of Energy Office of Science to be constructed and operated by MSU, is currently being designed to provide intense beams of rare isotopes to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions, and applications for society. The FRIB driver linac can accelerate all stable isotopes to energies beyond 200 MeV/u at beam powers up to 400 kW. Key technical R&D programs include low-beta cw SRF cryomodules and highly efficient charge stripping using a liquid lithium film or helium gas. Physical challenges include acceleration of multiple charge states of beams to meet beam-on-target requirements, efficient production and acceleration of intense heavy-ion beams from low to intermediate energies, accommodation of multiple charge stripping scenarios and ion species, designs for both baseline in-flight fragmentation and ISOL upgrade options, and design considerations of machine availability, tunability, reliability, maintainability, and upgradability. We report on the FRIB accelerator design and developments with emphasis on technical challenges and progress.